The UN's child agency believes one in five suicide attacks by Boko Haram are now done by children. Three quarters of the children used in such attacks are girls, says Unicef.

Despite the lengthy, high-profile #BringBackOurGirls campaign, 219 of them have yet to return home.

"Urgent action is needed, not only to protect the innocent. We need to prosecute the terrorists," Paul Coleman of the ADF International charity told HuffPost UK. "The human rights organisation is urging the International Criminal Court to finally hold members of Boko Haram to account."